The invention pertains to the general field of track-and-hold amplifiers. In particular this invention pertains to the development of programmable gain attenuators, so called PGAs, for track and hold amplifiers.
The general purpose of track-and-hold amplifiers is to accurately track an analog input signal and, at specified times, to accurately hold at its output for a certain length of time the instantaneous value of the input signal. This form of signal conditioning is particularly important ahead of analog-to-digital converters, where the quality of conversion is improved by maintaining a substantially constant value at the input of the analog-to-digital converter during the conversion process.
Programmable gain attenuators are used in various analog signal-processing applications where an electrical signal of varying amplitude must be either amplified or attenuated before subsequent signal processing. Various gain and/or attenuation settings are required to accommodate the wide dynamic range of the electrical signal.
Programmable gain attenuators for track-and-hold amplifiers are known from the state of the art. However as circuits become faster and faster there is a need for providing an improved PGA that can be used in these high frequency circuits.